It is known to provide a gauge for a slack adjuster, which includes a pointer mounted for movement with an end of a brake operating rod pivotally connected to a housing of the slack adjuster, and indicia applied to the housing, wherein the pointer swings across the indicia incident to pivotal movement of the brake operating rod relative to the housing for purposes of indicating the extent of travel of the brake operating rod relative to a brake release position. For example, reference may be made to U.S. Pat. Nos. 5,320,198 and 5,441,128.